Monoisobutyl phthalic acid is a phthalate metabolite that has been found in human meconium and in semen (PMID: 16970347 ), saliva (PMID: 15995852 ), and urine (PMID: 15113553 ). Phthalate esters are a family of multifunctional compounds widely used as plasticizers, solvents, or additives in many diverse products such as poly(vinyl chloride) (PVC) materials, pharmaceuticals and medical devices, pesticides, lubricants, and personal care products. Humans have been exposed to phthalates through the manufacture, ubiquitous use, and disposal of PVC materials and other phthalate-containing products. (PMID: 16970347 ).